Method of cutting woven plastic to form a displaced edge



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Aug. 15, 1950 Patented ug. 15, 1950 ivrsrnonY F CUTTING WoV-EN- PLAs'rIC l'ro y1ro-ninth DISPLACEDEDGE Robert Evans and ElnathanY H ,M|iller, -J r., Buffalo, NIX., assiglors to 'Bla S fel vPlasticsCor- Application July 13, 194.8.::Se1jal N O This invention relates lto certain new and useful improvements inl theI manufactlllemof products made from a threaded or woven plastic niaterial, such as watch straps, belts, etc.

It hasv for one of its vobjects to-so treat the material at those edges-thereof resulting lfrom tcuttns Qr-.punchnsa i0 prevent. its unravelina Anothercbiectf,thesnfflltiqn 1S t0: effect a heat treatment. oftheplasi:prQduCtS:in 5.11011 a manner and atuthe edges-or other warp-exposed -,areasandfsinflultaneously ,'With'sthe cutting or punchingoperationhas to causethe material ad- ;iacent such. edges@ 110W wemelt and-:thereby effect a self-sealing of the exposed edges in a beading or marginal fashion to positively prevent unraveling of the material at such edges or other areas.

A still further object is to provide a novel method of self-sealing the edges of the material or products of this character which is simple and efficient in operation, and which results in a neatly-finished edge.

In the accompanying drawings:

Figure 1 is a perspective view of a two-section, buckle type Watch strap showing the opposite edges and the edges about the row of buckle-engaging openings sealed by our invention. Figures 2 and 3 are enlarged fragmentary cross sections taken on the correspondinglynumbered lines in Figure 1. Figure 4 is an enlarged fragmentary cross section of the edge-seal effected when cutting the material into a given length for a watch strap. Figure 5 is a front View of the machine employed for cutting the strapping material into proper lengths and simultaneously sealing an edge thereof. Figure 6 is a front view of the machine employed for cutting the Waste from the strap-section, punching the holes therein for adjustable engagement with the buckle, and sealing the cut edge of such section and the edges about the punched holes.

Similar characters of reference indicate corresponding parts throughout the several views.

In the manufacture of threaded or woven products, such as watch straps, belts and the like made from a plastic or synthetic material like nylon, such products have a tendency to unravel at their edges or in other areas, as for example, about the openings or slots provided in watch straps or belts for rendering them adjustable by a lbuckle fitting. It is the purpose of our invention to so treat such edges as to effect their selfsealing to positively prevent unravelng and thereby maintain the product at all times neat in appearance and increase its duration of usefulness.

3 claims. (cruiser-fram Referring now to the drawings? showing an embodiment of the ,use O-,Qur ,invention4 as applied .to,a.Wo.ven, plastic w'atchstrapfby'way of .exarnple, le@ l4 indicate the complementary sec- .tions of such a strap, one having the' usualr row .of openings or perforations l2 therein for the adjustment of the strap on the wearer through 14the,medium of the customary buckle I3 borne by the therstrap-Section` The side or longitudinal ddg, v,en i'fhe strap are usually nished by hemy,ming protherwise, and in` manufacturing the straps they are cut into proper lengths from a reel `of`,strap-forming material, vsuch as,.woven v ;nylonkarid'rnnless,the cut edges forniedby the `warp threads are similarly hemmed or `finished the strap Will unravel.

We effect the finishing of the end edges and the margins about the perforations of the strap by a heat treatment simultaneously with that of the cutting and perforation-forming operations. To this end the strap-sections I l l are cut from a continuous strip of tape-like material applied to a reel I4 and from this reel the material is fed by hand or otherwise to a suitable machine, indicated generally by the numeral I5, and including a strap guide or table I6 and a verticallyreciprocating cutter l1. The table is preferably inclined, as shown, and the cutter is preferably arcuate in cross section so that the edge of the strap, when cut has a correspondingisloping or beveled edge I6, shown in Figure 4, of convex contour. This convex edge portion of the strap is subsequently folded and sealed upon itself to provide an attaching eye I9 for receiving the connecting pintle of the watch and this beveling out provides a feathering edge for a neat and smooth connection. The companion strap-section I l is provided with similarly formed eyes I9. The complementary concave portion in the resulting adjoining strap-section is merely waste and is subsequently removed. This latter operation may be accomplished, for example, in a suitable machine indicated generally by the numeral Eil for punching the perforations i 2 in the strapsection lll, and includes a horizontal strap-guide or table 2l, a row of vertically-reciprocating punches 22, and a like reciprocating cutter 23 of arcuate cross section to sever the waste portion from the strap-section and at the same time provide the latter with a convex edge at its free end.

These cutters are preferably made from stainless steel to withstand high temperatures and are heated to substantially a cherry red heat to approximately 1100 F. by means of gas jets 24 or the like which constantly play against the cutters during the operation of the respective machines l5 and 20. Thus, simultaneously with the cutting operations, the Warp edges of the strap contacted by the cutters are heated to a temperature to cause the material to fuse, melt or reach a fluid state and thereby eect the automatic sealing of the strap edges or the edges of the strapperforations. Furthermore, the initial melting takes place on the down-stroke of the cutters and punches, while on the upstroke the cutters and punches act to direct some of the marginal melted material toward the top surface of the strap where desired and by a wiping action provide a smooth-finished and sealed-over edging or beading 25, 26 at the end and about the performations of the strip to eiectually bond such edges and prevent their unraveling. The meltingV of the material provides a lm which sets and hardens within a relatively short period of time after the operating stroke of the cutters or punches on the strap-sections.

We claim as our invention:

l. In the manufacture of products woven from a plastic material, the method which consists of cutting the woven material to define an edge and simultaneously therewith subjecting the material in the vicinity of the cut to a temperature to fuse the portion contacted, and then by a wiping action displacing the fused portion of the material over the surace thereof to form an integral sealing-like iilm over the marginal portion of its cut edge.

2. In the manufacture of products woven from a plastic material, the method which consists of 4 cutting the woven material by a stroke-like action in one direction to define an edge and subjecting the material in the vicinity of the Cut to a temperature to fuse the portion contacted, and then by a wiping, stroke-like action in the opposite direction displacing the fused portion of the mate` rial over the surface thereof to form a sealing-l like bead over the marginal portion of its cut edge.- 3. In the manufacture of a perforated watch strap or the like woven from a plastic material, the method which consists of cutting the perforations therein and subjecting the Walls thereof to a temperature to fuse the same, and then by a wiping action displacing the fused portion 0f the material over the surface of the strap about the margins of the perforations to provide integrallyformed grommets about the same.

ROBERT P. EVANS.

ELNATHAN H. MIILER, Jn.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED sT'ATEs PATENTS Number Name Date 1,773,967 Dreyfus Aug. 26, 1930 1,871,897 Manheimer Aug. 16, 1932 1,978,620 Brewster Oct. 30, 1934 2,232,640 Schwartzman Feb. 18, 1941 2,328,063 Dodge Aug. 31, 1943 2,430,496 Dodge Nov. 11, 1947 2,438,156 Dodge Mar. 23, 1948 

